Subsurface injection valve system

ABSTRACT

A technique facilitates control over fluid flow via controlled operation of an injection valve. The technique enables control over operation of the injection valve in a variety of subsurface applications. The injection valve comprises a flapper which may be selectively shifted to and held in an open position. Depending on the operational configuration of the injection valve, the flapper may be shifted to the open position via fluid flow along a primary flow passage. However, the injection valve also may be shifted to the open position via a separate actuator controllable via pressure applied independently of fluid flow along the primary flow passage.

BACKGROUND

Hydrocarbon fluids, e.g. oil and natural gas, are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore is drilled, various forms of well completion components may be installed to control and enhance the efficiency of producing fluids from the reservoir. In some applications, an injector well is drilled and used for injection of fluids to facilitate production from a corresponding production well. An injection valve may be deployed with a completion string downhole in the injection well to enable control over the flow of injection fluid.

SUMMARY

In general, a system and methodology are provided for controlling operation of a subsurface injection valve in a variety of applications. According to an embodiment, the injection valve comprises a flapper which may be selectively shifted to and held in an open position. Depending on the operational configuration of the injection valve, the flapper may be shifted to the open position via fluid flow along a primary flow passage. However, the injection valve also may be shifted to the open position via a separate actuator controllable via pressure applied independently of fluid flow along the primary flow passage.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:

FIG. 1 is a schematic illustration of a well system deployed in a wellbore and including an example of a controllable injection valve positioned at a subsurface location, according to an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional illustration of an example of the injection valve, according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view similar to that of FIG. 2 but showing the injection valve in a different operational configuration, according to an embodiment of the present invention;

FIG. 4 is a schematic cross-sectional illustration of another example of the injection valve, according to an embodiment of the present invention; and

FIG. 5 is a cross-sectional view similar to that of FIG. 4 but showing the injection valve in a different operational configuration, according to an embodiment of the present invention.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

The disclosure herein generally relates to a system and methodology for controlling fluid flow, e.g. fluid flow during an injection operation. For example, an injection valve may be positioned in a well string deployed in a wellbore to control an injection fluid flow during a subsurface injection application. According to an embodiment, the injection valve comprises a flapper which is pivotably mounted in a valve housing to allow down flow of fluid and to automatically block up flow of fluid along the interior of the well string, e.g. along a primary flow passage of the well string. However, the flapper may be selectively shifted to and held in an open position to facilitate a variety of operations which utilize the interior of the well string.

The selective shifting and holding of the flapper in the open flow position may be accomplished via fluid flow along the interior of the well string and through the injection valve. For example, the flapper may be shifted by a flow tube having a restrictor such that sufficient fluid flow along the interior of the well string and through the injection valve causes the flow tube to shift into engagement with the flapper and to hold the flapper in the open flow position. However, the injection valve also may be shifted to the open position via a separate actuator, e.g. piston actuator, controllable via pressure applied independently of fluid flow through the injection valve.

In a specific embodiment, the injection valve is a subsurface injection valve which is in a normally closed configuration. In some applications, the subsurface injection valve is deployed along a well string and retrievable to the surface along the interior of the well string. In this and other embodiments, the injection valve combines an ability to shift and hold open the valve via a flow-induced pressure drop across a flow restrictor and an ability to open the valve via adjustment of a differential pressure, e.g. a differential between the primary flow passage and a tubing casing annulus, acting on a separate actuator. The flow restrictor may comprise an orifice, and the orifice may be a fixed or variable orifice disposed along, for example, a flow tube which interacts with a flapper of the injection valve.

By using a flow restrictor, e.g. orifice, along a movable member, the injection valve may be shifted to an open flow position without controlling or monitoring a tubing pressure or annulus pressure. The flow restrictor, e.g. orifice, may be sized according to a desired injection flow rate and the flow tube may be sized to cover and protect the flapper when the flapper is shifted to the open flow position. When the injection flow is stopped, the flow tube is automatically moved back to its original position and the flapper automatically closes.

In some applications, opening of the injection valve without flow therethrough may be useful. For example, some applications may employ a secondary valve downhole of the injection valve, and the secondary valve may be operated by pressure pulses or other pressure applied through the well string. Thus, it can be useful to open the injection valve for passage of the pressure signal to enable operation of the secondary valve when there is no fluid flowing through the well string. In other words, the separate piston actuator enables selective opening of the flapper without the sufficient fluid flow through the flow restrictor.

By way of example, the piston actuator may comprise a piston exposed to internal pressure within the well string or to annulus pressure along the exterior of the well string. The pressure may be used to shift the piston and to thus open the flapper without the sufficient injection flow passing through the flow restrictor of the injection valve. The pressure supplied to actuate the piston actuator also may be provided by other sources, such as an atmospheric chamber or an internal chamber pre-charged with nitrogen or other suitable gas.

Depending on the application, the injection valve and components of the injection valve may have various configurations. In some applications, for example, the piston may be in the form of a piston rod although the piston may have other forms, such as a concentric piston disposed around the primary flow passage. In some embodiments, the piston is coupled with the flow tube to move the flow tube although the piston can be coupled directly with the flapper. The piston also can be operated incrementally by, for example, supplying sequential pressure pulses to cycle the piston to different operational positions. By way of example, the piston may be coupled with an indexer, e.g. a J-slot indexer. In this latter example, pressure cycles along the annulus (or along another suitable channel) can be used to shift to the indexer and thus move the piston into various positions with respect to the flapper and/or flow tube.

Additionally, the flow restrictor may have various configurations. For example, the flow restrictor may be in the form of a retrievable orifice which can be selectively retrieved to the surface along the interior of the well string. The flow restrictor also may be a fixed size orifice, e.g. a fixed size choke plate, or a variable orifice, e.g. variable Venturi, variable nozzle, flow adjustable orifice, or other type of variable restrictor.

Referring generally to FIG. 1, an embodiment of a well system 20 for controlling flow of injection fluid is illustrated as positioned in a wellbore 22. In this embodiment, well system 20 comprises a well string 24 which may comprise a tubing string and may include various types of downhole equipment 26. The well string 24 and downhole equipment 26 further comprise at least one and sometimes a plurality of injection valves 28. The injection valve 28 is used to control a flow of injection of fluid along an interior 30 of a well string 24. The interior 30 forms a primary flow passage for delivering injection fluid downhole.

In the example illustrated, the well string 24 and the downhole equipment 26 also comprise at least one secondary valve 32, e.g. a ball valve, disposed on a downhole side of injection valve 28. In at least some applications, the secondary valve 32 is actuated via pressure applied along the interior flow passage 30 of well string 24. As described herein, the injection valve 28 serves to check unwanted flow up through the well string 24. However, the injection valve 28 also may be selectively shifted and held in an open flow configuration by sufficient down flow of fluid along interior 30 or by actuation of a separate actuator device via, for example, pressure applied independently of fluid flow along interior 30. The ability to shift and hold the injection valve 28 in an open position independently of fluid flow along interior 30 enables use of pressure pulses through injection valve 28 (or other actuation techniques deployed through injection valve 28) to selectively actuate the secondary valve 32.

Additionally, the downhole equipment 26 may comprise at least one packer 34 positioned to enable isolation of a well zone 36 along an annulus 38 disposed between an exterior of well string 24 and a surrounding wellbore wall. In some applications, the well string 24 may be in the form of an injection completion which may be deployed downhole and properly configured prior to isolation of zone 36 and injection of fluid into a surrounding formation 40.

Referring generally to FIGS. 2 and 3, schematic cross-sectional illustrations are provided of an example of injection valve 28. In this example, injection valve 28 comprises a flapper 42 pivotably mounted to a valve housing 44 via a pivot 46. In a no-flow condition, the flapper 42 is biased to a closed position against a corresponding valve seat 48 via, for example, a spring member 50. The valve housing 44 may be constructed with a variety of tubular sections coupled together via threaded engagement or other suitable engagement features.

Under normal operating conditions, fluid flow in the direction of arrow 52 along interior flow passage 30 causes the flapper 42 to open against the bias of spring member 50. (As illustrated, interior flow passage 30 extends through the interior of injection valve 28.) However, the flapper 42 quickly closes, as illustrated in FIG. 2, when the fluid flow 52 stops or attempts to reverse. In a variety of injection well applications, the flapper 42 is oriented to open and allow down flow of fluid along interior flow passage 30 while preventing up flow of fluid toward the surface.

In various stages of operation, however, it may be desirable to selectively shift and hold the flapper 42 in the open flow position, as illustrated in FIG. 3. The injection valve 28 comprises a flow tube 54 movably positioned within valve housing 44 along interior fluid flow passage 30. The flow tube 54 is selectively movable into engagement with the flapper 42 to shift the flapper 42 to an open flow position and to hold the flapper 42 in this open flow position regardless of the direction of fluid flow along internal flow passage 30. In FIG. 3, the flow tube 54 is illustrated in the engaged position holding flapper 42 in the open flow configuration. By way of example, the flow tube 54 may be constructed with sufficient length to at least substantially cover the flapper 42 and to protect the flapper 42 from fluid flows along interior passage 30 when the flapper 42 is held in the open position.

The flow tube 54 may be shifted to the engaged position holding flapper 42 open via fluid flow through a flow restrictor 56 coupled with the flow tube 54. As discussed above, the flow restrictor 56 may comprise a fixed orifice, variable orifice, or other type of fixed or variable flow restriction. The flow restrictor 56 is configured to restrict fluid flow along interior passage 30 while allowing some fluid flow through an opening 58. Thus, a sufficient fluid flow along the interior passage 30 of well string 24 and through flow restrictor 56 creates sufficient force to move the flow tube 54 into engagement with flapper 42 until flapper 42 is transitioned to the open flow configuration illustrated in FIG. 3. In some applications, the flow restrictor 56 may be in the form of an orifice comprising opening 58.

The flow tube 54 may be biased toward a disengaged position, illustrated in FIG. 2, which allows flapper 42 to pivot between open and closed positions. By way of example, a spring member 60, e.g. a coil spring, may be used to bias the flow tube 54 towards this disengaged position. In the illustrated example, the spring member 60 is positioned between a valve seat housing 62 containing valve seat 48 and an abutment 63 coupled with flow tube 54. The configuration of flow restrictor 56 and the spring force exerted by spring member 60 may be selected to establish the desired flow of fluid along interior passage 30 that will be sufficient to shift flow tube 54 and flapper 42 to the “held open” configuration illustrated in FIG. 3.

The injection valve 28 further comprises an independent actuator 64 configured to enable selective actuation of the flapper 42 to the held open configuration independently of fluid flow along interior passage 30. This allows the flapper 42 to be shifted and held in the open flow configuration even without flow along interior passage 30 in a direction of arrow 52. By way of example, the independent actuator 64 may comprise a piston actuator 66 having a piston 68 slidably received in a corresponding piston opening 70 formed within valve housing 44, e.g. within a wall of valve housing 44.

In the example illustrated, piston actuator 66 is coupled with flow tube 54 via a linkage 72. However, the piston actuator 66 also may be coupled directly with flapper 42. When sufficient pressure is applied within piston opening 70 on an opposite side of piston 68 relative to linkage 72, the piston 68 forces the flow tube 54 into the engaged position with respect to flapper 42, thus holding flapper 42 in the open flow configuration illustrated in FIG. 3. The independent actuator 64 thus provides an additional method for selectively shifting and holding flapper 42 in the open flow configuration.

Depending on the specifics of a given injection operation, the piston actuator 66 may be configured to expose piston 68 to internal pressure within the well string 24 or to annulus pressure supplied along the annulus 38. The pressure is supplied to selectively create a pressure differential able to shift the piston 68 and to thus open the flapper 42 without the sufficient injection flow passing through the flow restrictor 56. In an example, the pressure differential acting on piston 68 may be created by supplying a higher pressure through the annulus 38 compared to the pressure within interior flow passage 30.

It should be noted the actuator 64 may have various configurations. For example, the actuator 64 may be constructed with a single piston or a plurality of pistons in various shapes, sizes and configurations. In some applications, the piston 68 may be in the form of a piston rod, as illustrated in FIGS. 2 and 3, although the piston 68 may have other forms, such as a concentric piston disposed around the primary flow passage 30. The piston 68 also can be operated incrementally by, for example, supplying sequential pressure pulses to cycle the piston 68 to different operational positions. By way of example, the piston 68 can be coupled with an indexer, e.g. a J-slot indexer. When using an indexer, pressure cycles may be supplied along the annulus (or along another suitable channel) to actuate the indexer and to cause corresponding movement of the piston 68, flow tube 54, and/or flapper 42 into various positions.

Referring generally to FIGS. 4 and 5, another embodiment of injection valve 28 is illustrated. In this embodiment, many of the injection valve components are similar or the same as those illustrated in FIGS. 2 and 3 and are thus labeled with the same reference numerals. However, the pressure for selectively shifting piston 68 is supplied to piston opening 70 from a chamber 74 folding a desired pressurized gas, such as nitrogen. By way of example, the chamber 74 may be formed in a coil 76 charged with nitrogen or another suitable gas to a desired positive pressure. The shifting of piston 68 and flow tube 54 between the free flapper configuration illustrated in FIG. 4 and the held open configuration illustrated in FIG. 5 may be achieved by controlling the pressure differential between pressure within interior passage 30 and the pressure within coil 76.

Depending on the application, different types of gases and different configurations of chamber 74 may be utilized for establishing desired pressure differentials able to selectively shift flow tube 54 and flapper 42. In some applications, for example, the coil 76 may be used for containing atmospheric pressure which establishes a negative pressure. In this type of application, the spring member 50 and/or other spring members are positioned on an opposite side of the piston 68 so as to counteract the negative pressure of the atmospheric trap formed in coil 76. In this type of configuration, pressure differentials between the interior flow passage 30 and interior of coil 76 can again be used to selectively shift the flow tube 54 and flapper 42.

To accommodate various applications, the number and arrangement of injection valves 28 may vary from one injection well application to another. The injection valve(s) 28 may be utilized in both lateral and vertical wellbores to achieve the desired control over injection fluid flows into surrounding well zones. The injection valve 28 also may be used with many types of completion strings or other well strings to assist in a variety of production operations and/or other types of operations. Similarly, the configuration of each injection valve 28 and the components selected to provide control over the flapper by fluid flow or by pressure may be adjusted according to parameters of the application and/or environment.

Although a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Accordingly, such modifications are intended to be included within the scope of this invention as defined in the claims. 

What is claimed is:
 1. A system for controlling fluid flow, comprising: a well string having an injection valve and a secondary valve, the secondary valve being operated by pressure applied along an interior of the well string through the injection valve, the injection valve comprising: a flapper; a flow tube movable into engagement with the flapper to shift the flapper to an open position, the flow tube being movable by flow of fluid along the interior of the well string; and a piston actuator coupled with the flow tube to enable selective shifting of the flow tube and thus the flapper to the open position, the piston actuator being movable via pressure applied independently of flow of fluid along the interior.
 2. The system is recited in claim 1, wherein the flow tube is coupled with a flow restrictor.
 3. The system is recited in claim 2, wherein the flow restrictor comprises an orifice.
 4. The system is recited in claim 1, wherein the flow tube is spring biased toward a disengaged position relative to the flapper.
 5. The system is recited in claim 1, wherein the flapper is pivotably mounted in a valve housing and the piston actuator is disposed in a wall of the valve housing.
 6. The system as recited in claim 5, wherein the piston actuator comprises a rod piston.
 7. The system as recited in claim 1, wherein the secondary valve comprises a ball valve.
 8. The system as recited in claim 1, wherein the flapper is oriented to normally block flow along the interior in an uphole direction when the flow tube is in a disengaged position with respect to the flapper.
 9. The system as recited in claim 1, wherein the well string further comprises a packer positioned to enable isolation of an injection zone.
 10. A method, comprising: providing an injection valve with a flapper pivotably mounted in a valve housing along a flow passage; slidably positioning a flow tube in the valve housing for movement between a disengaged position with respect to the flapper and an engaged position which holds the flapper in an open position to fluid flow along the flow passage; coupling a flow restrictor to the flow tube to enable selective shifting of the flow tube to the engaged position via sufficient fluid flow along the flow passage through the flow restrictor; and using a piston actuator in cooperation with the flapper to enable selective shifting of the flapper to the open position independently of fluid flow along the flow passage.
 11. The method as recited in claim 10, wherein using comprises coupling the piston actuator to the flapper via the flow tube to enable selective shifting of the flow tube to the engaged position independently of fluid flow along the flow passage.
 12. The method as recited in claim 10, further comprising incrementally shifting the piston actuator via sequential pressure inputs.
 13. The method as recited in claim 10, further comprising positioning the injection valve in a well string.
 14. The method as recited in claim 13, further comprising deploying the well string downhole into a wellbore.
 15. The method as recited in claim 14, further comprising shifting the actuator piston via internal pressure applied along an interior of the well string.
 16. The method as recited in claim 14, further comprising shifting the actuator piston via pressure applied along an annulus surrounding the well string.
 17. The method as recited in claim 10, wherein coupling comprises coupling an orifice to the flow tube.
 18. A system, comprising: an injection valve having: a flapper pivotably mounted in a valve housing; a flow tube movably mounted in the valve housing for selective movement into an engaged position with the flapper in which the flapper is pivoted and held in an open position, the flow tube being movable by flow of fluid through the injection valve; and a piston actuator positioned for cooperation with the flapper to enable selective shifting of the flapper to the open position, the piston actuator being movable via pressure applied independently of flow of fluid along the interior.
 19. The system is recited in claim 18, wherein the piston actuator is coupled to the flow tube to enable selective shifting of the flow tube to the engaged position.
 20. The system is recited in claim 19, wherein the injection valve is part of a well string deployed in a wellbore. 